Base-exchange material and process of making same



Patented June 24, 1930 v UNITED STATES PATENT; OFFICE No Drawing. Application filed January 5, 1 926; Serial llo. 79,475.

This invention relates in general to the grains of exceptional hardness and duraproduction of base-exchange materials and bility. in particular to a new and improved process Attempts have been made to accomplish for preparing synthetically a double base anlincrease in the rweight and hardness of 5 exchange silicate of improved characterisbase exchange silicates made by wet methods tics; said silicate containing-a-larg'e proporby adding salts other than sodium salts to tion of silica and smaller proportions of the mixture. For instance, the use of iron alumina, sodium oxid and phosphorus oxid salts and of salts of alkaline earths has been (P and having a high density and hardproposed.

ness. We propose to attain the desired object Base exchange silicatesmade by the adby addmg solutions of a salt of aluminum mixture of solutions of salts of aluminum alone (that is,-without the salt of any other with a. solution of sodium silicate with submetal) to a solution containing sodium silisequent drying and granulation of precipi- Gate and the sodium salt of another element 1 tates formed in the reaction, are known and rather than to a solution of sodium silicate are commonly classed as base exchange subfll l stances formed by the wet method. The For our purpose we employ sodium phosprecipitate formed is always a, gel and may phate and our improved method of probe a jelly. The ordinary commercial prod cedure consists in the addition of a solution nets of the so-called wetmethod of producof aluminum sulfate to a .mixed solution 70 ing base exchange silicates by mixing solucontaining sodium silicate and sodium phos tions of aluminum salts and sodium silicate phate- I are in general characterized by their light 1 I s nc We may proceed as follows: weight and lack of hardness. We take 840 grams of degree B. sodium 25 An object of the pre ent inv ti i t silicate solution containing about 8.8 per 75 produce a granular base exchange silicate of 5- 9 of S0d1l1 111 Oxide and P cent high density and weight per cubic foot. q and IIllX this withglfio gramsfif This is of direct advantage particularly Q l m phosphate, bOth dissolved 1l1 .sl1fwhen suchsilicate is used fo if in or ficlent water to make the solution up to a 30 softening water, in that mat ri l f hi h total volume of six liters. This solution we density and weight per cubic foot is not so Shall g l zl l g fi di l h gig p a easily lifted by water flowing upwards $90011 11 y 550 P2; grams throllilgh it as abma tferial 0% less density and of 12111111111111? t i g 1n q -i ft v weig t per on 10 oot. n practical use ma 6 a a P 1 0 SIX 6 35 base exchange material is subjected to the then f Fq Volumes of solutlqns A and of upward-1y are when, the Emi ia-1125a iii i ioiv sireizasfi softener contalmng it is back-washed or f t d b when 1s employed a: angst Osage? that Base-exchange material of low density and 40 weight per cubic foot may be washed out of Product 18 thrown water whlqh cause-is th fie t hi h t f fl H it to break up into small particles. It is d g O eavy then washed and we thus obtain a hard,

ina erla 1s 0 abvantage in that e1ther less heavy, durable, ase exchange composition of rec-board may e allowed for the materlal high exchange capacity in the formpf Small 5 to Ilse P hlgher rates flow y be particles of great hardness. The weight of mp oy Wlth s d ng of s h q g this product is 60 pounds or more per cubic washing out of the softener than when hght f t, material 1s employed, Thisprocedure could be modified by mak- Another ob ect of the present nvention is ing the solutions of unequal concentration 50 to produce a base exchange sihcate with and unequal volumes of the two 10 foot, and by solutions, or di-sodium phosphate could be substituted for tri-sodium phosphate, in which case, however, we should either employ a sodium silicate having a higher content of sodium oxide or we should add less aluminum sulfate. 7

The essential principle of our invention is the formation of a base-exchange silicate of more than ordinary density and weight per cubic foot and hardness, by the addition of a solution of an aluminum salt, and particularly aluminum sulfate, to a mixed solution of sodium silicate and the sodium salt of some acid-forming element other than silicon, particularly sodium phosphate.

We claim as our invention:

1. The process which consists in prepar-' of aluminum sulfate, seping a solution arately preparing a mixed solution of sodium silicate and sodium phosphate, c0mbining the two solutions to form a gel and drying the latter at a temperature below the boiling point of water.

2. A base-exchange substance having a composition which, expressed in terms of oxides of its components, contains a large proportion of, silica, and smaller proportions of alumina, sodium oxide and phosphorus oxide, said substance being distinguished by a density sufficiently high to make it weigh at least pounds per cubic the property of being in the form of small particles of? great hardness.

3. In the manufacture of base exchange silicates the process which comprises gelling a solution containing alumina by one containing silica and a phosphate.

4:. As a new base exchange silicate a hydrated gel silicate containing alkali, alumina and P 0 and in the form of small hard particles.

5. In the manufacture of base exchange silicates in the wet way the process which comprises admixing a solution containing a silicate and a phosphate with a solution containing alumina.

In testimony whereof we have set our hands.

EDWIN M. PABTBIDGE. ELWOOD W. SCARRITT.

hereunto 

